U.S. Pat. No. 6,127,621 and U.S. Pat. No. 6,396,167-B1, issued to Simburger, teach a distributed power system where a power ring bus is used to connect multiple DC-DC converters in parallel with each DC-DC converter being connected to a solar cell or battery. Each DC-DC converter is supplied with an individual control regulator and supplied current to the bus based upon measurements of bus voltage of the power ring bus. Solar cells are body mounted on the various sides of the picosatellite. The power ring bus architecture solves the problem of obtaining the maximum amount of electric power from a solar array. The solar cell array has multiple panels that are arranged on a surface of the picosatellite. The parallel-connected regulators each include a boost converter, a pulse width modulator (PWM), and a voltage comparator circuit for performing the control function of regulating the amount of power to be delivered onto the ring power bus from a solar cell. The distributed power system has a loading problem. As the load increases on the power ring bus, the PWM increases the current output from the solar cell beyond the maximum power point for the solar cell thereby reducing the amount of power delivered to the power ring bus. Without peak power tracking, the regulator control circuit and implementation algorithm causes the output of the regulators to rapidly go to zero.
Another problem with the prior picosatellite distributed power system is an inability of the satellite to ascertain the operation efficiency of the solar cells, which may extend over several years of operation. For example, in a solar storm, solar cells can be damaged by radiation leaving the amount of power generation undetermined in the presence of fixed mission power requirements. Power systems on current satellite use shunt regulators or an unregulated bus to which the solar array is connected. Using an unregulated bus with shunt regulators, it is impossible to obtain the voltage current characteristic from the actual cells on the solar array. As such, the health of the solar array cannot be determined by a central processing system. With a centralized power system, there is usually a single regulator circuit, which controls all of the individual solar cell strings, or in the case of an unregulated bus, all of the solar cells are continuously connected to the bus. Thus, to measure the current and voltage characteristics of the actual solar array, the whole array must be driven from open circuit conditions to short circuit conditions. This is not possible for conventional solar arrays with conventional control architectures. These and other disadvantages are solved or reduced using the invention.